Construction workers have accidentally dug up a 40,000 year old tree that will give scientists insight into what will happen when Earth’s magnetic poles flip, which they are already starting to do

Every 200,000 to 300,000 years, Earth’s magnetic North and South poles swap places, an event that opens the planet up to solar radiation and coincides with major extinction events.We’re long over due for such an adventure, with the last pole reversal occurring 780,000 years ago.Earlier this year, NASA warned that the magnetic “north pole” is racing 30 miles-per-year toward Russia, signaling the beginning of a total pole reversal.The discovery of a tree that lived for 1,500 years during the exact same period of a near-reversal of the poles 42,000 years ago will now give climatologists new insight into what exactly that will look like.The ancient tree was found buried under 26 feet of soil by construction workers who were expanding a geothermal energy plant in New Zealand.The swamp kauri tree was preserved as if it were in a swamp, even though it wasn’t.It’s one of the oldest trees ever found. 65 feet long and 8 feet wide, the radioactive carbon in the tree’s rings provides a complete record of the near-reversal of the Earth’s magnetic fields that happened within the tree’s lifetime.

“Earth’s magnetic field is thought to be generated by the iron in the planet’s core,” Newsweek reports. “As it moves around, it produces electric currents that extend far into space. The magnetic field acts as a barrier, protecting Earth from the solar wind.”“When the magnetic field reverses—or attempts to—it gets weaker, leading to more radiation from the Sun getting through.”“There’s nothing like this anywhere in the world,” Alan Hogg, from New Zealand’s University of Waikato, told Stuff Magazine. “We will map these changes much more accurately using the tree rings.”While it can take several thousand years for the poles to completely flip, their journey to the other side can cause chaos in the meantime, as the lines of the magnetic field cross and get jumbled, weakening their ability to protect us from solar radiation.And they’ve already been on the move for 3000 years.Scientists are scrambling to create models to determine what that will look like on a practical level. This tree will help them do that.“As Earth’s magnetic shield fails, so do its satellites,” writes Jonathan O’Callaghan, a space journalist for Phys.org.“First, our communications satellites in the highest orbits go down. Next, astronauts in low-Earth orbit can no longer phone home. And finally, cosmic rays start to bombard every human on Earth. This is a possibility that we may start to face not in the next million years, not in the next thousand, but in the next hundred.”